The aural organism for African sleeping sickness is

The correct option is D Trypanosoma gambiense

African trypanosomiasis, also known as sleeping sickness, is an insect-borne parasitic disease of humans and other animals. It is caused by protozoa of the species Trypanosoma brucei. There are two types that infect humans, Trypanosoma brucei gambiense (TbG) and Trypanosoma brucei rhodesiense (TbR). Trypanosoma brucei gambiense causes 97% of human cases of sleeping sickness.

So, the correct answer is 'Trypanosoma gambiense'.